Unlike the regular Shock Baton, this weapon does no shock damage. When it scores a critical hit, the target will fall to the ground just like the knockdown effect of the Victory Rifle and the Gauss Rifle.
Enter the Engine Room during the generator-destruction phase of the main quest. Walk down the stairs and you will see a groove in the wall with a window. If you look through it you can actually see the weapon. Follow that corridor until you get into the big open area. Take a sharp left when you get to the open area, and then it will be your first left on the same wall you came in from. Go in that room and then follow the small corridor and at the end it will be lying on a table.
This weapon does not receive a bonus from the Xenotech Expert Perk. This may have been intentional because of its unique effects.